13th Greek/Australian International Legal and Medical

Conference

Judging Science

Chief Justice Robert French

30 May 2011, Kos

Nearly 40 years ago, as a newly minted lawyer who happened to have a

science degree with a physics major, I was keen to take on cases which involved

scientific questions. One such case concerned a young man riding a motor bike who

was clocked at twice the speed limit by a radar gun. He insisted that he had only

been travelling at the speed limit. The radar gun works by transmitting a radar beam

at a certain frequency. When that beam hits a moving object it is reflected back and

its frequency shifts upwards. This is called the Doppler Effect. The radar gun

combines the reflected signal with the outgoing signal to produce a resultant

frequency called the 'beat frequency' which is a function of velocity. According to

that beat frequency, the gun produces a readout of speed.

I remembered from my basic physics that the speed of a wheel at the top is

twice the speed at the axle. So if the motor bike were travelling at a speed 'V', the

spokes at the top of the wheel would be travelling at the speed 2V relative to an

external observer. Could this be the explanation for the disputed reading? Had

some of the reflected beam come off spokes travelling at twice the speed limit even

though the bike itself was travelling within the law? Could my client have been

telling the truth? I engaged the services of a PhD student. We brought to court a

bicycle wheel, a radio frequency generator and a couple of oscilloscopes. The

magistrate was transfixed by the evidence. However, he didn't know very much

about physics. In the end he said he would rely upon the policeman's personal

estimate of the speed and convicted my client. He was probably right to do so. His

approach had the virtue that he did not have to judge the difficult science put before

him. For the most part, however, scientific questions cannot be so easily side-

stepped by the courts. Every day, judges are asked to judge science.

2

Sometimes Parliament tries to save judges the trouble of judging science by

writing scientific propositions into the law and making them presumptively, or in

some cases conclusively, correct. Sometimes a law will provide that a certificate by

this or that class of expert or technologist on a matter of fact, such as the identity of a

substance which the expert or technologist has analysed, is to be taken as correct.

An early example of such provisions were regulations governing the use and

evidentiary effect of breathalysers in Western Australia in the 1970s. The

breathalyser readings were given presumptive force, but depended upon an

assumption about the relationship between the concentration of alcohol vapour in

alveolar air and the concentration in the blood. This was called the 'partition

coefficient' and was assumed to be 1500 to 1. The other assumption was used to

calculate back from the time the test was administered to the time at which the

accused had been last driving. The assumption was that alcohol was absorbed into

the blood stream at .016 per cent per hour for the first two hours after the last drink

and eliminated at the same rate thereafter – a handy linear relationship fairly

untypical of biological systems. That may have been because it was proposed to

Government by the Chief Government Chemist. The Chief Government Pathologist,

who had not been consulted, turned out to be a willing witness for the defence in

such cases pointing out the variability in partition coefficients and of absorption and

elimination rates in real people. He was a feisty Scotsman. On one occasion he was

asked by a frustrated police prosecutor whether there were not some people within

his profession who disagreed with him. He said: 'There are peculiar people in every

profession Sergeant, even yours.'

This talk is about judging cases in which evidence is given by people with

scientific expertise. I include in that category medical experts. The subject can be

approached at different levels. There are interesting questions about differences

between legal method and scientific method and whether they can ever properly

mesh or are fated to be like ships passing in the night. Those questions may be

answered differently depending upon whether the scientific method under

consideration is that of the researcher or that of the scientist who applies established

principles and/or technologies to draw inferences, make predictions or assess risks.

Their answers may depend upon differing approaches to factual certainty. Stephen

Jay Gould once said:

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In science "fact" can only mean "confirmed to such a degree that it would be

perverse to withhold provisional asset." I suppose that apples might start to

rise tomorrow but the possibility does not merit equal time in a physics

classroom.

Questions about the differences between legal and scientific approaches to factual

certainty have great inherent interest and practical significance. It is necessary,

however, for the purposes of this talk, to begin at a more concrete level by asking

what it is that judges and courts do when they decide cases. Like many legal

questions, the answer is not straightforward.

When a case comes before a court it usually involves a dispute about

somebody's rights or liabilities. The proceedings may be civil. Typically, in such a

case, one party sues another claiming some entitlement, such as damages for

personal injury, or for breach of contract or an injunction to restrain some wrong, or

a declaration of some right. The proceedings may be criminal, in which case the

State prosecutes someone for committing an offence.

The elements of judging can be expressed in what appears to be a simple

model of decision-making:

1. Identify the relevant rule of law.

2. Determine, after hearing the evidence, what the facts are.

3. Apply the rule of law to the facts to determine the rights and liabilities, if

any, of the parties to the case.

In a criminal case where the judge sits with a jury, the judge identifies the relevant

rules of law and tells the jury what they are and how to apply them to the facts. The

jury decides, on the evidence which it has heard, what the facts of the case are. The

jury applies the relevant rules of law to those facts as directed and finds the accused

guilty or not guilty, unless of course they can't agree, in which case they are

discharged and a new trial is started before another jury. The judge in such a case

acts as a gatekeeper on the evidence that can go to the jury. Where expert evidence

4

is called, the judge decides whether the evidence is admissible or whether its

probative value is outweighed by unfair prejudicial effects.

In both civil and criminal proceedings, arguments can arise around the first

step, namely, deciding what the relevant law is. The rules of law which are to be

applied by the courts are to be found in the Constitution of the Commonwealth or of

the States, in Acts of Parliament made under those Constitutions, in regulations

made under those Acts, and in judge-made rules, such as rules about contracts,

equity and torts like negligence or deceit. The legal environment in the modern

world does not offer exactness in the rules which have to be applied. That is not for

want of trying. Lawmakers often pursue certainty by writing detailed prescription

into statutes and regulations. This leads to longer Acts and more regulations. In the

musical 'Amadeus', the Emperor complained to Mozart after performance of one of

his works that it had 'too many notes'. Some statutes and regulations have too many

words. The more words there are the more room there is for debate about their

proper interpretation. The problems of interpretation thrown up by statutory

language often yield more than one possible solution. Language is plastic and

nuanced and has a history. For many words there is more than one core meaning

and there are penumbral meanings. Relevantly to this paper, statutes sometimes use

words importing concepts taken from or interacting with areas of specialised

scientific knowledge. Sometimes they do not do so accurately. Let me give an

example from a case which went all the way to the High Court.

In 1975, a young American woman was charged under the Customs Act 1901

(Cth) with importing into Australia a prohibited import, namely cannabis. The word

'cannabis' was defined in the Act as a cannabis plant or any part of a cannabis plant.

A cannabis plant was defined as a plant of the genus cannabis sativa. That definition

raised a difficulty because, according to the International Code of Botanical

Nomenclature, it was not proper to describe a genus by the use of two words unless

they were joined by a hyphen. Under the Code the second word 'sativa' denoted a

species.

At that time there were many botanists who took the view that the genus

cannabis had only one species, namely, cannabis sativa. That was the view that

5

prevailed when the definition was introduced into the Customs Act in 1971.

However, there was evidence of a different view among botanists that the genus

contained other species, cannabis indica and cannabis ruderalis. Those species could

be distinguished from cannabis sativa by their leaf and branch distribution. The

accused had brought her cannabis into Australia in the form of Buddha sticks. In

that form the cannabis is dried and crushed and rolled up. It was not possible to

determine whether it was cannabis sativa, cannabis ruderalis or cannabis indica. The

defence, therefore, was that the Crown could not prove that the imported plant was

of the prohibited species. At trial, expert witnesses for both sides debated whether

cannabis had only one species or more than one. The debate had raged between

competing experts in a number of court cases in the United States. Nothing

generates passion in the scientific breast like taxonomy. The evidence in the case

was about classification, rather than scientific inference. Once again, however,

science was side-stepped. The trial judge decided that whether or not there was one

species or more than one species of cannabis, the definition of cannabis in the Act

should be interpreted as applying to all species. That view was ultimately upheld in

the High Court.1 The Act was amended to make it clear that the cannabis plant

referred to was a plant of the genus cannabis.

That case focussed on the first step in the judicial process which I have

described, namely, the identification of the relevant rules of law. Three points come

out of it. The first is that the law may use words whose application may involve

scientific evidence, but may use the words in a way which does not fit comfortably

with the science. The second is that some scientific issues which come before the

court are really issues about taxonomy or classification. The third point is that a

legal rule may import a factual issue so that its interpretation may give rise to a

mixed question of law and fact.

______________________ 1 Yager v The Queen (1977) 139 CLR 28.

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Questions of fact – some categories

This paper is concerned principally with the second step in the judicial

decision-making process, the role of the court in determining the facts on the basis of

the evidence before it and the function of scientific evidence in taking that step.

There are different kinds of facts which may have to be decided. One kind is

historic – the answer to the question, 'what happened?' Another is predictive – the

answer to the question, 'what is likely to happen?' Another we might call the

retrospectively predictive – the answer to the question, 'what was foreseeable?' Then

there is the hypothetical – the answer to the question, 'what would have happened if

things had been done differently?'

Some questions of fact relating to the conduct of individuals involve

assumptions about the working of the human mind and use verbal constructs that

may engage, only with difficulty, with contemporary scientific knowledge.

Nevertheless, they state the terms in which a judge or jury must decide the case. An

example from the criminal law is the question, 'what was the intention of the accused

person?' A related question is, 'did the accused person lack the capacity to form a

particular intention because of intoxication or disease of the mind?' Another

question is, 'was the accused capable of controlling his or her actions?' The answers

of the judge or jury to these questions may be informed by medical evidence,

including psychiatric evidence, and that evidence sometimes has to be framed in a

way that engages with these non-scientific concepts.

Some questions of fact about conduct involve value judgments. Did

somebody take due care? Did somebody act reasonably or in good faith? Others are

really questions of legal classification, using language reflecting a classification

which may mean something to scientists but which does not necessarily carry the

same meaning in law. An example is the legal term 'a disease of the mind' which, for

a long time, was used as a point of reference in deciding whether a person suffering

from such a condition is criminally responsible for his or her actions. The medical

classification of a condition as a disease or a disorder involves evaluative judgments

made by those psychiatrists who decide what goes into such publications as the

Diagnostic and Statistical Manual of Mental Disorders. The recent compilation of

7

the 5th

edition of that Manual aroused debate about whether certain conditions such

as compulsive shopping or binge eating should be regarded as 'mental disorders'.2

Even here, evaluative and normative considerations may intrude into scientific

taxonomy. The distinction between the classification of some conditions as diseases

such as schizophrenia, and others as disorders such as psychopathy, may reflect

underlying normative or moral judgments. Expert witnesses may be called to give

evidence upon the basis of which the court will apply legal categories such as

disease or disorder. The judge, the lawyers and the experts should be clear in such

cases about the differences between the legal meaning of a term and the meaning

which the expert witness is giving to it, as well as the methodology underlying the

expert evidence.

Law borrows from science

Sometimes an Act of Parliament uses a term which is borrowed from, and

intended to incorporate, the methodology of a particular discipline. In such a case

the court can be assisted by experts from that discipline in applying the legal term.

Australia's competition laws prohibit various forms of conduct which substantially

lessen competition in markets for goods and services. The key concept of 'market' is

borrowed from the discipline of economics. Frequently, the debate in competition

cases is about the definition of the particular market. The larger the geographical

range of the market and the range of the products competing with each other in the

market, then the less likely it is that a particular firm's conduct will lessen

competition. So a judge may be confronted with competing expert evidence from

economists about the definition of the market. The regulator's economists may

propose a narrower market, while the defendant's experts will propound a wider

market.

______________________ 2 Carey, "Psychiatrists Revise the Book of Human Troubles", New York Times, 18 December

2008.

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In the late 1980s, the biscuit manufacturer Arnott's proposed to take over

another biscuit manufacturer, Nabisco. The Trade Practices Commission (now the

Australian Competition and Consumer Commission) went to court to block the

acquisition on the basis that Arnott's would be in a position to dominate a market for

goods and services if the acquisition proceeded. One of the questions concerned the

scope of the market. Was it just biscuits, or was it biscuits and non-biscuit products

such as Wagon Wheels, Rum Slices, After Dinner Mints and Snowballs.

In such cases, expert witnesses give evaluative evidence of an argumentative

nature. That is to say, based on economic theory, they will put an argument that the

best way of defining the market reflecting commercial realities and enabling

adequate predictions to be made about the effect of a merger, is to draw a boundary

around a particular set of products and a particular geographical range. Economists

in such a case may also give evidence about whether a particular course of conduct

is likely to cause, or has caused, a substantial lessening of competition in a market.

Similar evaluative or argumentative judgments are offered by anthropologists

in native title cases. Indigenous groups seeking recognition of their native title are

required under the current interpretation of the common law and the Native Title Act

1993 (Cth) to show that they are members of a society which was in existence at the

time that the Crown asserted its sovereignty over the land the subject of their claim

and that the society continues to exist today. The term 'society' was defined by the

High Court in 2002 as '… a body of persons united in and by its acknowledgment

and observance of a body of law and customs'.3 The determination by a court of

whether a relevant 'society' exists for the purposes of native title proceedings and

who it consists of involves drawing evaluative boundaries. This is particularly so

where a spectrum of similar traditional laws and customs are observed by groups of

Aboriginal people, distributed across substantial swathes of territory. In those cases

______________________ 3 Members of the Yorta Yorta Aboriginal Community v State of Victoria (2002) 214 CLR 422 at

425.

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the definition of the relevant society may be a matter of identifying a boundary not

unlike the process of defining the limits of a market in competition law. The expert

opinion in such cases, like that of economic experts, is by way of characterisation of

primary evidence and is essentially argumentative in character, even though that

characterisation is supported by relevant expertise.

Cause and causation

Perhaps productive of particular difficulty is the question whether one event

caused or contributed to another and, if so, to what extent? The factual question of

causal connection is not the same as the legal question of 'causation'. The legal

concept of causation involves the assignment of legal responsibility for things that

happen. This has typically been applied according to a test of what is called

'commonsense'. The leading case on this question March v E & MH Stramare Pty

Ltd4 was decided in 1991. It concerned an accident which happened at 1am on

15 March 1985 in Frome Street, Adelaide, not far from the intersection with Rundle

Street. A fruit and vegetable merchant parked his truck in the middle of a six-lane

road at 1:00 am in order to load it. His parking and hazard lights were on. A motor

vehicle was travelling in the lane nearest the centre of the road at an excessive speed.

The driver had a blood alcohol concentration of more than 0.18. The motor vehicle

struck the truck and the driver was injured. He sued the owner of the truck and the

driver of the truck. The High Court found that the truck driver's negligence was the

cause of the accident for the purpose of liability. It rejected a 'but for' test which

would have split responsibility between the truck driver and the driver of the car.

One area in which difficult questions of cause and effect can arise, is in the

application of epidemiological evidence. It arose recently in a case called AMACA

Pty Ltd v Ellis,5 which was decided in the High Court in November 2009. The case

concerned a man who died of lung cancer in 2002 at age 45. He had been diagnosed

______________________ 4 (1991) 171 CLR 506.

5 (2009) 240 CLR 111.

10

at age 43. He had smoked, on average, between 15 and 20 cigarettes a day for over

26 years before he was diagnosed. He had also been exposed to respirable asbestos

fibres during two periods of employment. The first was between 1975 and 1976

while working for the State of South Australia with asbestos cement pipes,

manufactured by AMACA, the former James Hardie Ltd. He was also exposed to

asbestos fibres while employed by Millennium Inorganic Chemicals Ltd between

1990 and 2002. His estate sued the State of South Australia, AMACA and

Millennium. The defendants were found liable at trial and appeals to the Court of

Appeal were dismissed. However, the appeal to the High Court was allowed.

The appeal was allowed on the basis that it had not been shown that asbestos

exposure had been a cause of the cancer. There was no medical evidence to say why

the deceased man had developed his cancer. Evidence was given of epidemiological

studies. Four experts gave evidence about relative risk that is, the ratio of the risk of

disease or death among those exposed to a carcinogen compared to the risk among

those not exposed. The relative risks assigned to smoking, according to the experts,

ranged from 7.7 to 20. The relative risk assigned to exposure to asbestos ranged

from 1.1 to 1.3. Evidence was given of the 'attributable fraction' among those

exposed, being the probability that the cancer in question was caused by exposure to

a particular carcinogen. Between the four expert witnesses, the probability that the

cancer was due only to smoking ranged from 67 % to 92%. The probability that it

was due only to asbestos ranged from 0.1% to 3%. The probability that it was due to

asbestos and smoking in combination, was said to range from 0.9% to 20%.

None of the witnesses was able to assign a probability greater than 23% to

the proposition that the cancer was caused by exposure to asbestos, with or without

smoking. The Court held that causation was not established and that the evidence

showed no more than that exposure to asbestos might have been a cause of the

deceased's cancer. The evidence did not show that it was more probable than not

that asbestos was a cause, in the sense of being a necessary condition for the cancer.

A passage in the Court's judgment throws up the difference between the

judge's function and that of the scientist:

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When, as here, medical and scientific examination cannot say whether

exposure to respirable asbestos fibres was a cause of Mr Cotton's cancer, the

medical practitioner and scientist have little choice but, as one witness said

at trial, to "take it into consideration in looking at what might have caused

his lung cancer". In their inquiries, the uncertainty about cause means that

they cannot "exclude it from the end result".

The court's response to uncertainty arising from the absence of knowledge

must be different from that of the medical practitioner or scientist. The

courts cannot respond to a claim that is made by saying that, because science

and medicine are not now able to say what caused Mr Cotton's cancer, the

claim is neither allowed nor rejected. The courts must decide the claim and

either dismiss it or hold the defendant responsible in damages.6

A history of scientific evidence in the courts

Historically, there have been three ways in which scientific or other experts

have been used in the determination of scientific issues in the courts:

1. To decide the question.

2. To assist the court to decide the question.

3. To give evidence as a witness for one of the parties.

The use of experts to determine disputed questions of fact requiring

specialised knowledge has a long history.7 For many centuries special juries were

used for that purpose in England. A woman sentenced to death could claim a stay of

execution if she could show that she was pregnant. In such a case the court could

direct a jury of 12 matrons to decide whether she was pregnant.8 It was common in

the 14th

century for the supervisors of various guilds to bring before the Mayor of

London offenders against trade regulations. A jury consisting of men in the relevant

trade would then be called upon to decide whether the defendant had offended the

______________________ 6 (2009) 240 CLR 111 at 121-122.

7 The history is set out in a celebrated article by Judge Learned Hand, "Historical and Practical

Considerations Regarding Expert Testimony" (1901) 15 Harvard Law Review 40.

8 A writ for the occasion known as a "Writ de Ventre Inspiciendo" developed. See Bracton De

Leg Lib II vol 69 cited in Learned Hand, above n 7, at 40.

12

trade regulations. That method was also adopted in cases brought by public

prosecutors and private citizens. In the 17th

century, a jury of merchants was used to

try merchants' affairs as they might have 'Knowledge of the Matters in Difference

which were to be tried than others could who were not of that Profession'.9

A second technique involved the court itself calling upon persons with

expertise whose opinion it might adopt, or not adopt, as it pleased. This technique

can be traced back to 1345 in a case in which the court summoned surgeons from

London to assist it in determining whether a wound was fresh.10

In 1494, 'Masters of

Grammar' were called upon to construe certain words in a bond. In 1555, courts

called in grammarians to help them interpret the pleas before them when the court

had some difficulty with the Latin.11

And since the 16th

century in England, judges

in admiralty matters have sat with Master Mariners of Trinity House to assist them

in assessing who was at fault in marine casualty cases. This custom was apparently

adopted from the International Court of the Councils of the Sea, which in earlier

times sat in Barcelona and settled disputes between members of the Merchants and

Mariners Guild.12

There are provisions under which Australian courts can appoint independent

experts to provide a neutral opinion to the court on a question of fact requiring

particular expertise.13

These provisions have not been widely used.14

This is not

______________________ 9 Learned Hand, above n 7, at 42.

10 Ibid.

11 Ibid.

12 Tal Golan, Laws of Men and Laws of Nature: The History of Scientific Expert Testimony in

England and America (2004) 20.

13 See, eg, Uniform Civil Procedure Rules 2005 (NSW), Pt 20, Div 3; Supreme Court Act 1935

(SA), s 67, Supreme Court Civil Rules 2006 (SA), r 208(2); Supreme Court (General Civil

Procedure) Rules 2005 (Vic), O 50; County Court (General Civil Procedure) Rules 2008 (Vic)

r 34A.22; Supreme Court Act 1935 (WA), Pt IV, Div 4; Supreme Court Rules 1971 (WA),

O 35; Federal Court of Australia Act 1976 (Cth), s 54A; Federal Court Rules 1979 (Cth),

O 72A.

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surprising in an adversarial system in which the parties want the facts to be

determined by the judge or by the jury and not by somebody else, and in which the

parties want to control the flow of information to the judge. A forensic concern

would be that a court-appointed expert may express an opinion which cannot bind

the court, but may nevertheless be more difficult to challenge or test than an expert

called by the opposing party. There may also be concerns about the extent to which

true objectivity would be achieved by even the most eminent court-appointed expert.

This is particularly so in the area of the social sciences and in economics and

anthropology.15

Having said that, even expert witnesses called by the parties are

expected not to be hired guns or advocates for the parties calling them. That is so

even when the testimony involves an argued evaluation. Evidence which lacks

objectivity will generally be discounted or disregarded.

Sometimes parties in dispute over a technical issue which requires expertise

for its understanding may, instead of going to court, refer the dispute to an expert for

what is called 'expert determination'. That is a process outside the court process. It

is related to, although not identical with, the process of arbitration.

In a sense, concerns about the objectivity of expert witnesses raise a larger

question about objectivity in science and applied sciences. Whether 'objectivity' is a

meaningful concept, and whether it is even theoretically achievable in scientific

judgment, may be the subject of a large debate. In an article about objectivity and

expert evidence, appearing in the Sydney Law Review in 2003, Gary Edmond

pointed to the context in which science today operates. There are social and

economic pressures, institutional politics, diverse funding arrangements, shifting

hierarchies and reward structures, ethical considerations, competition, complex

relations with other professions through activities such as patenting, sensitivities to

_______________________ 14

See, eg, I Freckelton and H Selby, Expert Evidence (4th

ed, 2009) 465.

15 See, eg, Federal Court Guidelines for Expert Witnesses.

14

public concerns, especially around risk, and changing public perceptions, levels of

trust and differing employment opportunities. He concluded:

… appeals to some extra-social image of objectivity become untenable and

expert knowledge becomes more complex and inescapably political. All of

the factors shaping the practices and production of knowledge raise very

serious implications for understanding the contemporary sciences as well as

the utility of simplistic images of objectivity and method.16

The complexity of scientific research and development was exposed in a case

on which I presided in 2007 involving a dispute about entitlement to patent rights

between the University of Western Australia and one of its professors, Dr Bruce

Gray.17

The case concerned the use of microspheres for delivering different

therapies to liver cancers. The development of the technology took place over more

then 20 years. It involved a variety of funding sources and collaborations and

varying institutional arrangements. It occurred within a legal setting defined in part

by the researcher's contractual relationship with the University, the University of

Western Australia Act 1911 (WA), the operation of the University's statutes and

regulations, its organisational structures, commercialisation processes and the

general framework of the law relating to fiduciary duties and the entitlements of

inventors. Illustrative of the demands upon modern medical researchers, there was

evidence of innumerable applications for research grants, large and small, for

general and highly specific purposes, each of which had to demonstrate the utility

and value of the proposed use of the funds and things which had been achieved up to

the time of the application.

The resolution by courts of disputed questions of fact involving scientific

theory or its application today generally involve the use of expert witnesses called by

the parties. That is the most common way in which law and science intersect within

______________________ 16

G Edmond, "After Objectivity: Expert Evidence and Procedural Reform", (2003) 25 Sydney

Law Review 131 at 134-135.

17 University of Western Australia v Gray (No 20) (2008) 246 ALR 603.

15

the court. The use of expert witnesses in this way dates back to at least the 17th

century.18

One of the earliest reported English cases which turned into a battle of

experts was Folkes v Chadd, decided in 1782. The silting up of Wells Harbour in

North East England was blamed on developers who had constructed embankments in

the vicinity to counteract natural tidal flooding and allow them to open up land for

agricultural use. The Harbour Commissioners sued the developers. The

Commissioners produced a long line of pilots, mariners and others to testify about

the rapid deterioration of the harbour. The developers, towards the end of the case,

produced a rather arrogant expert witness who told the jury that the Commissioners'

witnesses were 'unfamiliar with the true principles of nature …' and that they had

been 'misled by their own perceptions'.19

The Commissioners appealed on the basis

that they had been ambushed by this evidence. On appeal, the parties were ordered

to exchange the opinions of their experts. The developers secured the services of

England's leading civil engineer, John Smeaton. The Commissioners tried to hire

him as well. He suggested that he act as an adjudicator rather than as a witness, but

the Commissioners declined his offer and called four senior engineers as their own

witnesses instead.

In the event, Smeaton's evidence at trial was rejected by Chief Justice Gould

because it was based on a hypothetical natural process that could not be measured or

otherwise verified, making it 'no foundation for the verdict of the jury'. The jury

found in favour of the Commissioners.20

The developers appealed on the basis that

their expert's evidence had been wrongly rejected.

On appeal, Lord Mansfield held that Mr Smeaton's opinions should have

been received. He said:

______________________ 18

Golan, above n 12, at 41.

19 Ibid at 22-23.

20 Ibid at 39.

16

I cannot believe that when the question is whether a defect arises from a

natural or artificial cause, the opinions of men of science are not to be

received … The cause of the decay of the harbour is also a matter of science

and still more so now that the removal of the bank can be beneficial. On

this, men such as Mr Smeaton alone can judge. Therefore we are of opinion

that his judgment, formed on facts, was very proper evidence.21

The rise of the expert witness has also seen the rise of many species of

expertise not always grounded in a body of scientific knowledge. This is sometimes

referred to in the United States as 'junk science'. In his Principles of Judicial Proof

published in 1892, Professor John Wigmore quoted a passage about expert evidence

from a text of the day called 'Hints on Advocacy':

[As] the diversity of climes and soils produce diversities of trees, so the

various kinds of contentious legal businesses give rise to a vast variety of

witnesses.22

The observation remains valid. The myriad subject matters upon which courts are

required to make decisions inevitably attract many different kinds of claimed

'expertise' which it is said will assist them in their determinations. Their varieties are

distinguished by more than their subject matters. Some areas of claimed expertise

fall outside the field of science altogether. The essence of a scientific theory is its

'falsifiability, or refutability or testability', as Karl Popper said. A statement of

theory is 'falsifiable, if and only if, there exists at least one potential falsifier – at

least one possible basic statement that conflicts with it logically'.23

That proposition

was quoted with approval by a majority of the Supreme Court of the United States in

the case of Daubert v Merrell Dow Pharmaceuticals Inc.24

As one of the Justices,

Blackmun J observed in that case:

______________________ 21

[1782] 3 Doug KB 157 at 159.

22 J Wigmore, Principles of Judicial Proof (1892) 423.

23 Karl Popper, 'Realism and the Aim of Science' From the Postscript to the Logic of Scientific

Discovery, (3rd

ed, 1983) at xx.

24 509 US 579 (1993).

17

Science is not an encyclopaedic body of knowledge about the universe.

Instead it represents a process for proposing and refining theoretical

explanations about the world that are subject to further testing and refining.25

There are areas of so-called pseudo science which consist of a body of assertions

based on a theory which has not been subject to any experimental testing. It is

unlikely that a party who produced an astrologer to explain or excuse particular

behaviour or to predict events by reference to the alignment of the stars at a given

time, would be allowed to adduce such evidence.

On the other hand, new technologies and new scientific methodologies

emerge from time to time which, after repeated exposure in the courts become

accepted as based upon an appropriate body of scientific knowledge. It is important

that the probative value of such evidence be tested because, as the Supreme Court of

Canada said in 2000, evidence can be accepted, by a jury, as being virtually

infallible when it is dressed up in scientific language which a jury does not easily

understand and is submitted through a witness of impressive antecedents.26

It is interesting to see the reaction of courts to new technologies when they

first appeared. The District Court of Colorado in Smith v Grant, one of the first

cases to deal with x-ray evidence, said in 1896:

We have been presented with a photograph taken by means of a new

scientific discovery the same being acknowledged in the arts and in the

science. It knocks for admission at the temple of learning and what shall we

do or say? Close fast the doors or open wide the portals? These

photographs are offered in evidence to show the present condition of the

head and neck of the femur bone which is entirely hidden from the eye of the

surgeon. Nature has surrounded it with tissues for its protection and there it

lies hidden; it cannot, by any possibility, be removed or exposed that it may

be compared with its shadow as developed by this new scientific process. In

______________________ 25

509 US 579 at 590 (1993) quoting Brief for American Association for the Advancement of

Science et al as Amici Curiae at 7-8.

26 R v DD [2000] 2 SCR 275 at [39].

18

addition to these exhibits in evidence, we have nothing to do or say as to

what they purport to represent; that will, without doubt, be explained by

eminent surgeons.27

There was much early scepticism about fingerprint evidence, a scepticism

expressed in the Supreme Court of Victoria in 1912 by Chief Justice Madden who

said:

We are asked to accept the theory that correspondence between two sets of

fingerprints is conclusive evidence of the fact of the identity of the person

who made those fingerprints as an established scientific fact standing on the

same basis as the propositions of Euclid or other matters vouched for by

science and universally accepted as proofed.28

New technologies are intruding upon the legal process, probably with greater

frequency today than at any time in history. The rise of forensic science in the

investigation and detection of crime is well known. The law here intersects with

fields such as forensic chemistry, toxicology, biology, mineralogy, serology and

pathology. Forensic science provides techniques and tools for criminal investigation

and prosecution that could scarcely be imagined even as recently as 25 years ago. It

has the capacity to support determinations of guilt and innocence. But bad forensic

science also has the capacity to seduce and mislead. A leading Australian example

was the Chamberlain case.29

The judicial process did not discover the mistakes that

lead to the wrongful convictions in that case. It took a Royal Commission to do so.

That is not to say that the accuracy and reliability of such evidence has not greatly

improved since that time. Improvements to the processing and handling of evidence,

including preservation of original samples, have resulted from the errors uncovered

by the Chamberlain Royal Commission and other incidents. The challenge in

communicating such evidence in a comprehensible way to courts and, in particular,

to juries, remains ongoing.

______________________ 27

29 Chicago Legal News 145 (26 December 1896)

28 R v Parker [1912] VLR 152 at 154.

29 Chamberlain v The Queen (No 2) (1984) 153 CLR 521.

19

Beyond judging the reliability of the particular scientific method or

technology that is brought to court, the judge may have to decide whether a witness

is speaking within his or her area of expertise. Rules of evidence have been

developed in Australia and in other jurisdictions to prevent judges and juries from

being misled by experts who reach beyond their expertise. This involves, in a direct

way, judging whether the claimed expertise derives from a body of specialised

knowledge based on training, study or experience.

Under the Evidence Act 1995 (Cth), expert evidence is admissible as an

exception to the opinion rule. Under the opinion rule, an opinion is not admissible to

prove the existence of a fact about the existence of which the opinion was expressed.

This scepticism of lay opinion reflects an observation attributed to Hippocrates that:

There are in fact two things, science and opinion, the first begets knowledge,

the latter ignorance.

There are a number of exceptions to that rule and the exception relevant for present

purposes is that relating to expert evidence. Section 79 of the Evidence Act

provides:

If a person has specialised knowledge based on the person's training, study

or experience, the opinion rule does not apply to evidence of an opinion of

that person that is wholly or substantially based on that knowledge.

Whether a witness's field of expertise confers on them the requisite

specialised knowledge is a matter for the judge to decide. The precise line is

sometimes difficult to identify. The modern trend in the cases has been towards a

narrow construction of the scope of an expert's field of specialised knowledge in

order to ensure that evidence received by the courts is based on specific knowledge

of a particular area, rather than general expertise. By way of example, a person

qualified as a psychologist has been held not qualified to give an opinion on

20

psycholinguistics.30

In the case in question, Justice Brennan held that a

psychologist's report and statement of qualifications failed to reveal the requisite

expertise necessary to enable him to form a view about the accused person's

understanding of particular questions or his use of particular words or phrases. In

2007, the South Australian Supreme Court held that a qualification in nuclear

physics and extensive reading of papers on HIV-AIDS did not qualify a person to

give evidence that there was little or no scientific basis for the proposition that HIV-

AIDS is sexually transmitted. In a similar vein, an experienced emergency surgeon,

in the same case, was also found to have knowledge of HIV-Aids derived from

reading the literature which did not qualify him to give his particular evidence.31

Difficult science

There are cases in which factual questions must be answered which require

the court to have a grasp of a mix of difficult scientific and evaluative issues. One

such field, not necessarily the most difficult, is that of biotechnology. Not

surprisingly, biotechnological issues arise in disputes about patents for inventions.

When the holder of a patent for an invention sues somebody for infringement

of the patent, the court has to decide whether the allegedly infringing product falls

within the description of the invention as set out in one of the claims in the patent.

Typically the defendant will counter-attack by alleging that the grant of the patent

itself should be revoked on one or more of a variety of grounds. One such ground is

that the invention as claimed would have been obvious to a person skilled in the

relevant art in light of the common general knowledge as it existed before the

priority date of the claim.32

______________________ 30

Murphy v The Queen (1989) 167 CLR 94.

31 R v Parenzee [2007] SASC 316.

32 Patents Act 1990 (Cth), s 18(1)(b)(ii) and s 7(2).

21

There has been much judicial exposition of the language of the relevant

provisions of the Patents Act 1900 (Cth) and much discussion of them among

academics and practitioners who specialise in the field. It is enough for present

purposes to say that a court asked to judge whether a claimed invention was obvious

has to put itself in the mind of a skilled worker in the field and consider whether that

worker would have found the invention to be an obvious step given what was

already known. In the case of a biotechnological invention, the skilled worker

would ordinarily be a person with a PhD or some other post-graduate qualification in

the field. In such a case, the court will be provided with a body of evidence about

the state of common knowledge and published literature in the area relevant to the

invention. It is likely to hear conflicting expert opinions about the state of

knowledge and what might have been inferred from it at the relevant time. If the

parties are sensible, they will at least propose an agreed prima to the court covering

the essential scientific background so that the court can better understand the

evidence.

A case in which this was well done was one in which I sat on the Full Court

of the Federal Court in proceedings between the drug company Pfizer, which held

the patent for Viagra, and Eli Lilly Company, which manufactured Cialis.33

In that

case, Eli Lilly had begun proceedings against Pfizer alleging its patent was invalid

on a number of grounds including obviousness. Pfizer counterclaimed, alleging that

Eli Lilly was infringing its patent by the manufacture and sale of Cialis.

The obviousness question, which was one of a number of issues in the case,

involved a basic understanding of the physiological and biochemical processes at

work in the erectile function. Much of this was common ground and well explained

in an agreed PowerPoint presentation by counsel. The obviousness judgment

required consideration of a number of prior art publications in scientific journals.

______________________ 33

Pfizer Overseas Pharmaceuticals v Eli Lilly & Co (2005) 225 ALR 416.

22

The active ingredient of Viagra is a compound which blocks the ability of an

enzyme, called Phosphodiesterase 5, to lower the concentration of a certain

messenger chemical designated by the initials cGMP. By so doing, it facilitates the

relaxation of smooth muscle cells which is necessary for an erection to occur. It was

important in developing the drug that the relaxant effect not extend to other organs

of the body, such as the heart or lungs.

An important paper, published before the priority date for the Viagra

invention, recounted an experiment using strips of penile tissue taken from 21 men

who had been treated with prostheses for impotence. The strips were mounted on

wire in organ bath chambers and electrically stimulated. In the course of the

experiment a relaxant response was enhanced by the addition of a cGMP PDE

inhibitor called zaprinast. A large number of researchers, medical specialists and

pharmacologists gave evidence at trial. In the event, the Court concluded that the

inventive step was not an obvious one in light of the prior art. The English courts

came to a different conclusion. Without going into the detail of the reasoning and

the argument, this case is a good illustration of the way in which the courts can be

confronted from time to time with factual questions dependent upon scientific

evidence, involving the application of evaluative concepts such as 'obvious'.

Whether an invention is obvious or not, is not a question which can be answered

simply by the application of scientific knowledge. The criteria for obviousness

import policy considerations. How high or low the bar is set will affect perceptions

of incentives for research.

The more technically or scientifically complex that an issue is for

determination the greater the challenge for the courts, whether in patent law or in

other fields. In some areas involving computer science and complex software, the

complexity of the issues may test the limits of the capacity of the courts to answer

the composite questions of science and law to which they give rise. The courts have

attempted to mitigate these difficulties by procedural and case management

mechanisms. Expert witnesses are required to understand that they are not hired

guns and that they owe a duty to the court. It is not unusual for experts on both sides

of a case to be directed to have a conference before the hearing to reduce their points

of different so far as possible. In some cases, the less adversarial presentation of

23

experts' evidence allows their testimony to be given in a kind of conversation with

each other and with the court, which is said to assist with communication and

comprehension.

Conclusion

The challenge of judging science is more readily met by judges and lawyers

who have a basic scientific literacy. It requires also a commitment by expert

witnesses and lawyers to clear explanation of the scientific opinions advanced in a

case. All experts are required to ensure that the court is aware of the facts and

assumptions upon which their opinions are based. The court also needs to be able to

understand the process of reasoning which leads to the opinion that is offered to the

court. And that will ordinarily require some explanation of the underlying scientific

principles and methodology which is being applied. This is subject to agreement

between the parties to narrow the issues on which expert evidence is given to

exclude matters which are not in dispute.

There are, undoubtedly, transaction costs associated with having courts

determine scientific questions as part of the fact-finding process of the judicial

function. Ultimately, however, those who come to court do not expect the judicial

function to be handed over to a non-judicial expert, however eminent and well-

qualified. The function of the court is to identify the law, ascertain the facts and

apply the law to the facts in a public and principled way that reaffirms the rule of

law to the parties and to the wider community. And, if in doing so, the court must

make difficult judgments about science that is simply part of the job.